What Are Seed Oils: 6 Harmful Effects to Know

Many reasons account for the rapid increase in the rate of chronic diseases in humans1. Some of the reasons are consuming sugar, saturated fat, and other harmful chemicals in the form of food.

The lesser known fact is one of the major causes of this is the industrial seed oils as well. We have been consuming these products as cooking oils regularly without knowing the harmful additives used in the making.

Let us look at what are seed oils and the health risks that they cause.

1. What Are Seed Oils?

Popular industrial seed oils are processed oil extracted from various food items like soybeans, rapeseed plants (the source of canola oil), corn, safflower seeds, and cottonseed. These oils were in the 1900s to the American diet.

Then how did these highly processed oils make their place in the diet worldwide? The story is quite strange.

In the 1870s, two soap makers decided to enter the business together. Since the historical method of making soap was different, this pair wanted to try something new. They tried making soap with vegetable oils.

During this time, oil was discovered in Pennsylvania as well. They used cottonseed oil for lighting purposes and considered it a fuel.

It was then considered a “toxic waste” until the new soap-making pair wanted to make soap with it.

They thought that it would be a great idea if they could produce soap from the wasted cottonseed oil.

During the process, another thought strikes their head. They thought of altering the components and combination of the cottonseed oil 2by a chemical process and using it as a cooking oil.

It marked the beginning of “toxic waste” used for cooking purposes in America.

raw seeds and seed oil
Image from Shutterstock

In no time, all the other seed and vegetable oils followed. Soybean oil started to gain popularity. It became one of America’s most popular vegetable oils by the 1930s.

Soon, many oils like safflower oils, canola oil, corn oil, and sesame oils were introduced into Western culture. The low price and great marketing made these oils popular in every kitchen in Western Asia.

The Harm-

Modernization has helped us in many ways but has proven to be a curse for our bodies. The daily lifestyle we follow has adverse effects on our bodies.

The sleeping pattern, lifestyle, and poor human diet have immense negative effects on our bodies.

Purchasing industrial seed oils and processed foods has increased as they are cost-effective. Regular intake of these foods and oils has increased the chance of chronic diseases in humans.3

It is one of the main reasons why the life span of humans is decreasing at an alarming rate.

Many dietary factors, like the consumption of refined sugar, gluten, and industrial seed oils, have increased inflammation in our bodies.

They have increased the risk of chronic inflammatory diseases and made it hard to control and manage blood sugar levels.

The consumption of these foods also makes us tired and causes flare-ups in the brain.

2. What Are Seed Oils Made Of?

Industrial seed oil manufacturers use many steps to refine and process common seed oils extracted from various substances.

Oils extracted from corn, cottonseed, soybean, safflower seeds, and rapeseed plants are processed through many steps.

All these oils are refined, bleached, and deodorized to make them fit for human consumption. The steps that include processing these common seed oils are mentioned below.

seed oil
Image from Shutterstock
  1. At first, the seeds are gathered from various substances like safflower, rapeseed, soybean, corn, and cotton.

  2. Then these seeds are heated to extremely high temperatures, which causes the oxidation of the unsaturated fatty acids. The process is responsible for creating harmful byproducts that harm human health.

  3. After the oxidation is complete, the seed is further processed with a petroleum-based solvent. The best petroleum-based solvent is hexane, which maximizes the amount of oil extracted.

  4. In the next step, chemicals are used to deodorize the oils that form an off-putting smell after the oil is extracted. In the deodorization process, trans fats are produced, which have been proven to have harmful additives that cause a threat to human health.

  5. In the last step, more chemicals are added to these oils to make the colour more pleasing and remove any bad odour.

3. Reasons Why Seed Oils Are Harmful To Human Health

Mainly, six main problems that make industrial seed oils harmful for consumption. 4The oils increase the chances of chronic inflammation and also is one of the main causes of heart disease.

Studies show they are the main culprits for chronic diseases like coronary heart disease.

Let us take a detailed look at the main problems that these industrial seed oils have.

3.1. Evolutionary Mismatch

Intake of refined sugar, industrial seed oils, and excess calories represent an evolutionary mismatch.

Till the 1900s, industrial seed oils were not popular among humans. We did not use it for cooking purposes.

But from 1970-2000, the use of industrial seed oils hiked to the maximum. The consumption increased from 4 pounds per person to 26 six pounds per person yearly.

The total calories provided by linoleic acid, which is one of the main fatty acids used in industrial seed oils, is 8%. At the same time, our ancestors’ total calorie intake from linoleic acid was merely 1-3%.

Much research says that our body is not designed in a way that can withstand this quantity of linoleic acid. As a result, we are the victims of so many chronic diseases.

3.2. Improper Omega-6 To Omega-3 Ratio

Some essential fatty acids are polyunsaturated fats required in our bodies, but we cannot make them ourselves.

As a result, we have to consume these substances as food consumption. They are found in omega 3 fatty acids and omega 6 fatty acids.

Omega 6 fatty acids are known for producing potent metabolites and arachidonic acid. 5These are pro-inflammatory.

Consumption of omega-3 fatty acids gives rise to anti-inflammatory derivatives. Some popular examples of omega-3 fatty acids are EPA, ALA, and DHA.

A proper balance between the quantities of omega-6 fatty acids and omega-3 fatty acids is required to maintain optimal health in our bodies. The ratio of these fatty acids in our ancestral health was 1 to 1.

At the same time, the ratio maintained these days is 10 to 1 and 20 to 1. Eating more omega-6 fatty acids and fewer omega-3 fatty acids is responsible for creating an imbalance in our bodies.

The imbalance is one of the major causes of numerous diseases.

peanuts and oils in a container ,
From UnlimPhotos

3.3. Seed Oils Are Unstable

The polyunsaturated fats6 in the seed oils make them highly unstable. These fats easily oxidize the industrial seed oils when exposed to light, heat, and more chemicals.

After exposure to these chemicals, two harmful byproducts are created: liquid peroxides and trans fats.

Trans fats are one of the main ingredients responsible for cardiovascular diseases and type 2 diabetes. On the other hand, liquid peroxides are harmful substances that are known to destroy the DNA, membrane lipids, and protein throughout the body.

When the liquid peroxides accumulate in the body in larger quantities, the body starts to promote aging and increases the chances of chronic diseases.

3.4. They Have Many Additives

Synthetic antioxidants are added to the industrial seed oils to prevent oxidation and rancidity, as the fatty acids in the industrial oils are very unstable. These synthetic antioxidants7 have problems too.

BHA, BHT, and TBHQ are some synthetic antioxidants that have immune-disrupting, carcinogenic, and endocrine-disrupting effects.

In addition, TBHQ increases the immunoglobulin E response to food allergens. Once this response is released, the antibodies are released, and as a result, it causes food allergies.

3.5. They Come From Genetically Modified Crops And Plants

Apart from being nutrient-poor, the maximum quantity of industrial seed oils is derived from genetically modified plants. They also have toxic byproducts and unsavoury chemicals that harm human health.

Some of the top genetically modified crops used in the industrial seed oil-making process are cotton, soy, corn, and rapeseed.

According to research, 93% of soybean, 88% of corn, 93% of rapeseed, and 94% of cotton plants are genetically modified in the United States.

3.6. They are Heated Repeatedly

Repeatedly heating industrial seed oils is another reason for the deterioration of our health. Heating it from time to time for restaurant and household purposes magnifies its effect on our bodies.

Though reusing the same oil makes it cost-effective, it has a dreadful effect on the human body. It makes the oil full of toxic byproducts whose intensity of causing harm increases.

Heating the industrial seed oils over a long period depletes them from the vitamin E level and induces the formation of free radicals. These free radicals damage our bodies’ DNA, protein, and lipids.

It is also the main cause of the formation of oxidative stress in our bodies. It is one of the main reasons industrial oils are responsible for heart disease, high blood pressure, and liver and intestine damage.

4. Problems Caused Due To Industrial Seed Oils

seed oil
Image from Shutterstock

These highly processed oils cause many problems. They have several health risks that turn into serious problems over time.

Some of them are mentioned below.

4.1. Asthma

Consuming industrial seed oils is one of the main causes of asthma. Intaking omega 6 fatty acids in a greater quantity than omega 3 fatty acids increases the pro-inflammatory mediators.

These mediators are associated with asthma and, as a result, cause asthma in our bodies.

4.2. Autoimmune Disease

Industrial seed oils are the main reason for causing autoimmune diseases in humans.8 The improper intake of omega 6 to omega 3 fatty acid ratio promotes autoimmunity.

It does so by increasing the level of oxidation stress and chronic inflammation.

4.3. Mental Health And Cognition

It has been seen that industrial seed oils are harmful to mental health as well. The imbalanced intake of omega 6 to omega 3 fatty acids is the main cause of depression, anxiety, dementia, and cognitive decline.

If you have Alzheimer’s disease and tend to take Canola oil, it is likely to worsen memory and cause problems in learning ability. The trans fats present in industrial seed oils cause dementia and aggression.

4.4. Obesity And Diabetes

Studies say that industrial seed oils will likely make us obese and diabetic.

According to research, the primary fatty acid in industrial seed oils is linoleic acid which is known to alter the neurotransmission signaling that increases the amount of food consumption and fat mass in mice.

A diet high in soybean oil provided to mice shows that it increases the level of obesity and diabetes. It is also known to increase the chances of fatty liver diseases.

It is also seen that canola oil causes insulin resistance in animals.

Human studies also show that one of the major causes of diabetes and obesity in adults and children is the regular intake of industrial seed oils.

If a maternal diet consists of more omega-6 fatty acids than omega-3 fatty acids, the child will likely suffer from obesity.

If the food system of a child consists of more omega-6 fatty acids, then the child is most likely to be prone to prediabetes and many severe health problems in the future.

Girl testing diabetes on glucose meter in park
From UnlimPhotos

4.5. Heart Disease

In contradiction to the statement of AHA, industrial seed oils and the human heart can never be good friends.

The oxidized fatty acids in industrial seed oils play a very important role in human formation of cardiovascular diseases.

James DiNicolantonio, a famous researcher in his research of “oxidized linoleic acid theory of coronary heart disease,” said that,

  • The dietary linoleic acid present in the formation of industrial seed oils is directly incorporated into the lipoproteins of the blood.

  • The instability of linoleic acid causes lipoprotein oxidization in the blood.

  • These oxidized lipoproteins get unrecognized by their respective receptors. It, therefore, activates macrophages known to intimate the foam cell formation in the body. In addition, it also causes cardiovascular diseases and atherosclerosis.

Cardiovascular diseases are caused by the excess intake of omega-6 fatty acids as they are known to have prothrombotic and inflammatory effects on the vascular system of our bodies.

Studies also show that regular canola and soybean oil intake contributes to various heart diseases.

4.6. IBD And IBS

In much research, it has been seen that industrial seed oils are the major contributor to bad gut health, which leads to severe conditions like IBS (Irritable Bowel Syndrome) and IBD (Inflammatory Bowel Disease).

According to research, a diet containing omega-6 fatty acids increases the pro-inflammatory gut bacteria in mice. These bacteria are the main cause of chronic diseases related to gut health.

An elevated amount of arachidonic acid is found in women with IBS, a mega-6 fatty acid in various industrial seed oils.

Abundant pro-inflammatory PUFA metabolites have also been found in humans due to the excess intake of industrial seed oils.

These are the major causes of diseases like IBS and IBD in humans.

Consuming more omega-6 fatty acids is the main reason that promotes inflammation in the intestine, leading to many serious stomach-related problems.

As most of these problems are caused due to the excess intake of omega-6 fatty acids to omega-3 fatty acids, it is suggested that we start consuming alternatives like natural fats from coconut oil, olive oil, nuts and seeds, wild seafood, and healthy animal fats.

4.7. Inflammation

The maximum intake of omega-6 fatty acids leads to chronic inflammation. Partially hydrogenated and non-hydrogenated soybean oil is associated with increased C – C-reactive protein levels in our bodies.

It also causes the elevation of interleukin-6 and TNF-alpha, also known as systemic inflammation biomarkers.

4.8. Infertility

According to research about the United States men and women, 11 percent of women and 9 percent of men in this country suffer from impaired infertility.

One of the highly overlooked factors for infertility is the intake of an improper ratio of omega-6 fatty acids to omega-3 fatty acids.

It has been seen that the quantity of omega-6 fatty acids is higher in infertile men than in infertile women.

Not only in humans, but research on female mammals also showed that excessive intake of omega-6 fatty acids causes poor reproductive outcomes.

4.9. Macular Degeneration

Not only for the body, but industrial seed oils are also harmful to the eyes. Consuming a high amount of omega-6 fatty acids increases the risk of being affected by age-related macular degeneration.

Macular degeneration is an eye disease in which people lose their vision and eventually go blind. Regular intake of omega-6 fatty acids in larger quantities can replace the omega-3 fatty acid, which is also essential for the human eye.

4.10. Osteoarthritis

Portrait of a female doctor talking to an elderly patient about osteoarthritis
From UnlimPhotos

People who have symptoms or signs of osteoarthritis are advised not to consume industrial seed oils regularly. The omega-6 fatty acids in these highly processed oils are hazardous to bone health.

5. Cooking Oils To Be Used

Instead of industrial seed oils, there are other seed oils or other oils that can be used for cooking.

Some of these oils are mentioned below.

5.1. Extra Virgin Olive Oil

Olive oil has been a popular part of the human diet for many years. It is rich in vitamin E, polyphenols, and antioxidants.

Additionally, olive oil has many health-promoting properties like anti-diabetic and cardioprotective properties.

5.2. Coconut Oil

Coconut oil is a famous oil used in cooking various dishes worldwide as it is rich in various health-promoting properties.

It has medium-chain triglycerides like fatty acids and lauric acid, which are used by our bodies for generating energy.

It also has antibacterial, antifungal, and antiviral properties essential for the human body. The presence of 90 percent saturated fats in coconut oil makes it a very heat-stable oil.

5.3. Ghee And Butter

If you are not lactose intolerant, butter and ghee are the best oil substitutes. It will add an extra flavour to whatever dish you are cooking.

Butter and ghee from grass-eating animals contain a large amount of conjugated linoleic acid. It is a fatty acid that contains anti-cancer and many other healthy fats.

Apart from that, it also contains a lot of other health-promoting properties.

For the ones who are lactose intolerant, you can opt for ghee rather than butter, as all the milk constituents in ghee are removed during processing.

Bowl of ghee, or clarified butter, used extensively in Indian cooking.
From UnlimPhotos

5.4. Pastured Lard

It may appear surprising to many, but pastured lard is one of the widely used substitutes for industrial seed oils.

It contains monosaturated fat that is also present in olive oil and is termed “heart-healthy” by many doctors and medical experts.

People who cannot tolerate butter can use lard as a substitute. Lard is the fat obtained from pigs with a high content of saturated fats. It is the best supplement for butter in a lot of recipes.


By the end of this article, we hope you are clear about what are seed oils and how they can cause harm to our bodies. It is the most advertised and most harmful ingredient for the human body.

It has a lot of harmful effects and is one of the main causes of chronic diseases in humans. You can use many alternatives in the market to make your dish taste even better.

Changing your seed oils to some healthy substitute is never too late.

Make sure to use these highly processed oils as little as possible and to a quicker option at the earliest.

Frequently Asked Questions (FAQs)

1. Is olive oil a seed oil?

No, olive oil is not a seed oil but a vegetable oil as it is made by pressing whole olives.

2. Is coconut oil a seed oil?

No, coconut oil is not a seed oil as it is made from the meat of the coconut.

How Bad Is Trans Fat For Your Health
Icy Health

  1. Yach, Derek, et al. “Global chronic diseases.” Science 307.5708 (2005): 317-317. ↩︎
  2. Cherry, J. P. “Cottonseed oil.” Journal of the American Oil Chemists’ Society 60.2Part2 (1983): 360-367. ↩︎
  3. Booth, Frank W., and Simon J. Lees. “Fundamental questions about genes, inactivity, and chronic diseases.” Physiological genomics 28.2 (2007): 146-157. ↩︎
  4. Ganesan, Kumar, Kumeshini Sukalingam, and Baojun Xu. “Impact of consumption and cooking manners of vegetable oils on cardiovascular diseases-A critical review.” Trends in Food Science & Technology 71 (2018): 132-154. ↩︎
  5. Needleman, Philip, et al. “Arachidonic acid metabolism.” Annual review of biochemistry 55.1 (1986): 69-102. ↩︎
  6. Calder, Philip C. “Polyunsaturated fatty acids and inflammation.” Prostaglandins, leukotrienes and essential fatty acids 75.3 (2006): 197-202. ↩︎
  7. Augustyniak, Agnieszka, et al. “Natural and synthetic antioxidants: an updated overview.” Free radical research 44.10 (2010): 1216-1262. ↩︎
  8. Davidson, Anne, and Betty Diamond. “Autoimmune diseases.” New England Journal of Medicine 345.5 (2001): 340-350. ↩︎

Last Updated on by ayeshayusuf


Annanya Chakraborty
Apeksha soni

Leave a Reply

Your email address will not be published. Required fields are marked *